#1207 (comment)

Vite's current biggest performance bottleneck is first page load with large amount of modules. This is mostly caused by congestion at the browser network layer, since every module results in a full HTTP GET request on fresh server start.

To improve this, we can dump the in memory transform cache to disk on server close, and "hydrate" the module graph on next server start (the hydration should only fill in the cache for files with still fresh mtimeMs). The cache can be dumped in one file so it should be relatively fast to deal with. This allows the server to directly send 304s even on a restart.